The Panoramio was a world known photo sharing service allowing people to upload photos and place them on map. It was sold to Google. Then google decided to close it, effectively destroying community gathered around Panoramio. For the sake of integrating it with google maps.
Another, maybe not so known Polish service digart is going to be shut down this month. It is also photo and graphic sharing service with community, which was sold to large Polish portal Onet. Again all of the people (yes people, not users!) creating community are left with option to just download their photos, having all their contributions vanished.
Original authors of those websites are upset with decision of new owners. It seems that many web applications are being abandoned by big players, for which relatively small community is meaningless. There are many more cases like this. The only solution might be that web applications should be paid, thus allowing original authors to keep them indefinitely. As long as community is willing to keep their assets on application. So that owners would not be forced to sell their creation along with people.